Screen-camera calibration using a thread

In this paper, we propose a novel screen-camera calibration algorithm which aims to locate the position of the screen in the camera coordinate system. The difficulty comes from the fact that the screen is not directly visible to the camera. Rather than using an external camera or a portable mirror like in previous studies, we propose to use a more accessible and cheaper calibrating object, i.e., a thread. The thread is manipulated so that our algorithm can infer the perspective projections of the four screen corners on the image plane. The 3-dimentional (3D) position of each screen corner is then determined by minimizing the sum of squared projection errors. Experiments show that compared with the previous studies our method can generate similar calibration results without the additional hardware.